Automatic pilot for airplanes



April 2, 1929.

L. B. SPERRY AUTOIATIC PILOT FOR AIRPLANES Original Filed Sept. 13. 1919 SSheets-Sheet 1 INVENTOR [A w/mvm fijPm/i'x April 2, 9- L. BQSP'ERRY 1,707,690

AUTOMATIC PILOT FOR AIRPLANES Original Filed Sept. 13. 1919 5 sheetssheet 2 5 19115. Q 46' w///4 H; II

April 2, 1929. L. a sp m 1,707,690

AUTOIATIC PILOT FOR AIRPLANBS Original Filed Sept. 13. 1919 3 sh t -sh t 3 v INVQENTOR: lnunavcmfipmx Patented *A pr.

' UNITED STATES PATENT o-Fncs.

I mwanncn 1B. srmmy, o1- omannn CITY,

NEW, Yonx, AssroNoB, BY MESNE AssummEm's, T0 srnnmz cmscorn comm; nm, A conrom'rron or mm Your.

AUTOMATIC PILOT IOBAIBPLAm.

Application and September 13, .1919, Serial in. 323,464. l'enewedlibecember 1a, 1928.-

This invention relates' to the control of airplanes. Heretofore airplanes have been provided with automatic control means and with manual control means connected with the automatic control, so that the automatic piloting means could beadjusted by the aviator to cause the machine to fly in any desiredmanner, Also .it has been customary to provide an'independent manual control for use when the automatic pilot was not in use. Such control systems have involved numerous parts and complex connections be.-

tween the manual adjustment, the automatic control, and the straight manual control. In the simplified control system which I have devised, however, the automatically operated control surfaces can be .over-controlled at operated directly by the aviator.

the will of the aviator by the operation of a separate set of control surfaces, and the necessity for adjustments of the automatic pilot rendered unnecessary. To this end Ihave provided, inaddition to surfaces operable directly by the aviator, a separate auxiliary set of automatically operated "control surfaces, the operation of the automatically operated control surfaces. having less effect upon the airplane than the operation of the control surfaces which are In this manner 'the efiectof the automatic control can be modified to such an extent that themovement of'the airplane in any plane can be controlled by the operator directly regardless of the action of the automatic control surfaces, but at the same time the advantages of automaticstabiliz'ation in all planes'retained. A still further improvement in operation. is attained, since by employing smaller control planes with the automatic pilot the so called hunting action or jerkiness of the control is largely eliminated even through 11 follow-up system be employed. A simple a d reliable control, either manual or automatic, is also secured.

Referring to the drawings in which Ihave shown what I now consider to be the preferred embodiment of my invention:

Fi l'is a perspective view of an airplane provided with a plurality of sets of rudder and stabilizing surfaces.

Fig. 2 is adiagrammatic view of one form the usual control steering gyroscope whemthe operator actua'tes the control means for the steering rudder.

An airplane 1, of any suitable construction, is shown provided with a set of control surfaces adapted to be actuated directly by the aviator, and consisting of a steering rudder 2, a horizontal rudder 3, and a set of ailerons 41-4, and with a separateset of automatically operated auxiliary control surfaces consist ing of a steering rudder 2', horizontal rud ders 33', and ailerons 4 4'. Each auxiliary control surface is. designed to exert'on the airplane a smaller turning movement than the corresponding manually operated control surface, and accordingly I have illustrated each auxiliary control surface as of less area than the corresponding manually operated control surface, though, of course, the turning moment of any ofthecontrol surfaces may be varied by varying its effective lever arm rather than its area, as is shown by placing surfaces 4'4 nearer the center line of the craft than surfaces 4 -4.

Various means for enabling the aviator to actuate thecontrol surfaces 2, 3, and 4 may be utilized. I have shown one such means by way of example in Fig. 2. While steering rudder 2 may be connected, as by wires 5, with any suitable lever, pedal, or the like,

I have shown it connected to the extremities Y are closed. Spring 10 is sufiiciently powerful that rudder 2 may be operated by pressure on either of parts 7-8 'of pedal 6 without separating contacts 11 and 12, butif sufiicient force be applied to both parts 7 i and 8 simultaneously, contacts 11 and 12 may be separated. The purpose ofcontacts 11 and 12 will appear later. Horizontal rudder 3 is shown connected by wires 13, 13 with control lever 14, pivoted at15 to rockshaft 16.

j 2e 27 is energized, the

'For operating the ailerons 4, 4, a cable or wire'17 is shown directly-connect1ng said ailerons, while a second cable or wire-18 1s scope 21 of thetype disclosed in my copend connectedat its ends to both ailerons and at its center to an arm 19;-project1ng from rock-shaft 16." Suitable pulleys 20 may beprovided for guiding-wires .17 and 18,- and puIl'eys'20' may be provided for guiding the wires controlling the auxiliary control sur faces. For automatically controlling the auxiliary'steering rudder 2 I may employ a gyroing application No. 112,505 for gyroscopic pilot for aeroplanes, filed August,1, 1916. As

i there disclosed, the steeringgyroscopic unit .-'comprises a gyroscope mounted on a horizontal spinning axis and controlling the steering rudder thru a set of contacts 24 connectcd to, the gyroscope mounting to which are connected wires 22 and 23 A contact brush 25 is pivotally mounted on a relative- 1y fixed part of the airplane. Brush 25 can be 'moved .withreference to .gyroscopically controlled contacts 24 by nieans of a followup connection from the auxiliary steering 4 I rudder 2',

sists of wires 4L leading from 'a' drum 40 on a shaft of aservo motor to be described later. As before stated, however, this follow-up connection may be omitted entirely, if de sired, since the small automatic control shr ,faces cause a more vgradual turning of the azimuth takes place between the gyroscope airplane than is caused by theusual automatic control surfaces of larger area, and the hunting of the'airplane is to a great ex-} tent eliminated. When relative movement in and airplane a circuit is closed thru one or .the other of wires 2223 and hence thru one orthe other of coils 26 27 of a servo motor will bethrown against disk 36, and shaft 35 willbe revolved to actuate the auxiliary vermotor tical steering rudder 2 through' bevel gears 37+38 and wires 39. J v

I The details of the preferred fornrof servo for this and similar uses, are fully described in my copending application-now matured into Patent No. 1,415,003 dated May 2, 1922, for automatic pilots for aeroplanes and consequently further detailed description of the servo motor will not be given here.

For automatically controlling both the 1on gitudinal and lateral stability a gyroscope 42, of the type disclosed in my aforesaid Patent #1,'415,003, may be used. Asexplained which follow up connection con-' in said patent, the gyroscopic unit comprises a .pendulous gyroscope mounted on a vertical spinning axis and {controlling both the longi tudinal and lateralg'controls by==two sets of contacts 43-44 positioned so as'to be moved 1 and airpla'neabout either axis.' Contacts by th'erelative-movement of the gyroscope.

44,:which, with the airplane flying in. the di-- rection'of the arrow 45, would govern the longitudinal stability, aremounted. on the are secured to'a swinging loop 47 connected to the gyroscope so as to remain fixed with respect to the longitudinal axis.

9 As in the case with the steering gyroscope, the cooperating "brushes may be provided horizontal gimbal ring 46, while contacts 43 With afollow up system it desired, although, l

a follow up system is not such a necessary element in this invention as in my former in ventiong For this purpose, arm, 48, which supports brush 49, is pivotally mounted and secured to a pulle' 50, around which the follow up wires 51 trom the auxiliary horizon tal rudders 3 extend. Likewise,brush 52 is connected to a' pulley 53 over which follow up wires 54 are placed leading from the auxiliary ailerons'4,

From the foregoing description it is evi-l' dent that relative movement a out a horizonatal'a xis between the airplane and gyroscope will result' in brush 49 engaging one of con- "tacts 44, whereupon a circuit will be closed thru one or. the other of coils 55, 560i servo motor 57, with the result that the auxiliary horizontal rudders 3 will be moved thru gear 79' and wires 79 in one direction or the other: Likewise, relative movement aboutthe longiplane and gyroscope will result in the closing of a circuit through one or the other of coils 5859 of servo motor 60, with the result that auxiliary gear 80 and wires 80.

tudinal axis of the airplanebetween the airailerons'4 will be operatedthru The windmill 31 may be.used to generate bothdirectand alternating current, by communicating'its rotation t'oja direct current I generator and to a'separatealternating 'cur-' rent generator. II have shown the d1rec tcur-- rent generator diagrammatically at 61 as furnishing current for the coils of the servo- .motors. The alternating current generator isshown diagrammatically at 62, and may vhave its field 63 excited from the direct current'machine. The alternating current gen-v orator 62, as shown, is ol'th'e three, phase type,

the generator being an' indu'ctor alternator, 1

whilethe gyro motors'are three phase induc- I ti'on motors and are driven from saidgenejrator, the windings 64,65, being placed on the staors ofith'e corresponding gyroscopes- 21 ani42.--

satisfactory for l temporary changes in the inclmation or course of the machine but, for

The apparatuslso -far described would I .a permanent change, it" would advisable and.even necessary to provide additional means to cause the automatic pilot to steer the machine on the new course when the manual control is released as otherwise the mapermanent change, of course is only effected in azimuth, I have shown such means as appliedto the vertical rudder 2 only.

One of the simplest methods of altering the automatic control in azimuth is'to lock the control gyroscope 21 to the machine when it is desired to alter the course and to release it again when the machine is headed in the new desired direction, asdisclos'ed and claimed broadly in my aforesaid co-pending ap lication for gyroscopic pilot for airplanes, erial No. 112,505, filed August 1, 1916. For this purpose, I have provided means acting auto- .matically, whenever the aviator actuates pedal6, with sufiicient force, for centralizing and locking the yroscope with relation to the airplane, so t at, after the gyroscope is unlocked n'o circuit will be closed thru either coil of the servo motor 28 as long as the airplane keeps on-its new course in azimuth.

I have shown in detail in Fig. 4, a tapering or conical shaped member 66, which is adaptedto be moved'toward the gyroscope to engage a stem 67 extending therefrom. Memher 66 is provided with a rearwardly project ing stem 68 slidable in a bearing 69 and carrying a pin 70. A lever 71 is ivoted at 71 and has'a forked end 72 whic engages pin and a. forked end 7 3 which engages pin 7 4 on the movable core 75 of solenoid 76. When said solenoid is energized the member 66 is retracted and the gyroscope 21' is unlocked with respect to the airplane. When, however, said solenoid is decnergized, a spring 77, attached at one end .to lever 7 -1,and at its other end to a bracket 78, moves member 66 into position for locking the yroscope with respect to the airplane, so t at no current will flow thru contacts 24 and 25'.

While solenoid 76 might be energized from an independent circuit, I have shown it, in Fig. 3, connected to the direct current generator 61. In series with said solenoid are contacts 11 and 12. Ordinarily, when rudder 2 is operated by actuation of either part 7 or 8 of pedal 6, said contacts remain closed, due to the strength of spring 10, but if it is desired to deenergize solenoid 76, the aviator may actuate both parts 7 and 8 of pedal 6 simultaneously, thus compressing spring 10 sufliciently to separate. contacts 11 and 12 and turn the rudder while the contacts are open. Wires .5-5 should of course be sulficien'tly flexible or have suflicient slackto per-.

mit both parts of pedal 6 to be actuated simultaneously. -The circuit thru solenoid 76 is thus broken, and spring 77 moves tapered member66 into position to'centralize and 4 regardless of the action of the automatic control surfaces. After actuation of members 2, 3 and 4 has ceased, the automatic control stabilizes the airplane longitudinally and laterally and returns it to its original course in azimuth unless the operator has previously caused contacts 11 and 12 to separate, in

which case the airpan'e will continue in azimuth on the course resulting from actuation of rudder 2 while the contacts were sepa-- rated.

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of my invention, to gether with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention.can be carried out by other means. Thus it will be understood that manual control devices, by Which the plane is controlled at will, are illustrative only and that my invention is adapted to aircraft having any form of control whetherit be directly from the operator in the plane or otherwise. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be aI- control surface or surfaces for turning the airplane up or down, of a separate control surface or surfaces for performing the same functionof less turning effect than the first mentioned control surfaces, and means brought into action when the airplane turns up or down for operating the separate control surfaces automatically.

2. In an airplane control system, automatic means for controlling allmovements of the ,airplane about both horizontal axes, and separate controllable'at will means of greater turning effect than said automatic means for controlhng the movements of the airplane about the said axes, whereby said automatic means may be overcontrolled at the will of the o erator.

(l I v 3. n an alrplane controlsystem, means "ments of the airplane about sai .responsive to movements of the airplane about a lateral axis for controllin the moveaxis, and separate means 0 erable simultaneously with and independently of the first mentioned means, forcontrolling the movements of the airplane about the same axis, said separate means having a greater turning effeot than said first mentioned means.

4. In a control system for airplanes, a plu- .rality of independently operable control surfaces for governing the movements of the airplane about the same axis, means for controlling oneof said surfaces, automatic means for controlling another of said surfaces, and

' means controllable by operating the first named means for rendering said automatic means inoperative. a

5. In a control system for airplanes, a plurality of control surfaces, controllable means for operating \one surface, automatic means for operating another surface, means for normally maintaining said automatic means operative during the operation of said controllable means, and means cooperating with said controllable means for rendering said automatic means inoperative during the operation of said controllable'means. c

'6. In an aircraft control system, a plurality of control surfaces for governing the movements 1ofthe aircraft about a plurality of axes, means res nsive to turning of the craft about each 0 the several a xes for con trolling the surfaces for governing the craft about said axes, and aseparate set of manu- {ally operable controlasurfaces of greater ,turmng effect than the first mentioned concontrolling one surface;

. rality of control surfaces rality of control trol surfaces for modifying the effect of the lattersurfaces at the will of the aviator. for aircraft, a plul.7. Iira controlsystem adapted to control the aircraft about the same axis, means for means including a gyroscope for controlling another surface, and means associated with the first mentioned 8. In a control system for aircraft, a plusurfaces, means for controlling one surface, means including a gyroscope for controlling another surface, and.

means associated with :the first mentioned -scope for controlling anoth means for'locking the gyroscope tothe aircraft. I Q

ling one surface, In ans including a gyroer surface, T and means associatedwit'h the firstw mentioned 10-. In a'control-system'for .1 or controlling another" 7 means for centralizingthe gyroscope with re- Specttothe-aircraft.

aircraft, a plurality of control surfaces, means for controln s r .me fis ncl i g ally operable means tional means.

' eluding ll gy l'Cb Sur ace, and

i 4 means associated with the first mentioned means for centralizing and locking said gyrofor controlling the same about a plurality of axes, means adaptedto automatically maintain a position fixed with respect to space for governing said controlling means, additional means for controlling said craft about said axes and adapted to overcome said first named controlling means and means operable at will for governing said additional means. Y Y

12. In combination with an aircraft, a steering rudder therefor, an automatic pilot device for. controlling said rudder, an, additional steering rudder of'greater turning effeet for said craft, means operable at will for controlling said additional rudder and means selectively operable from said first-named means for. alteringthe relationship between said device and the aircraft. I

13; Incombi nation with an aircraft, means or controlling the stability of said craft, means adapted to maintain a plane fixed in space adapted to govern said 'controlling means, additional means'for controlling the stability of said craft and having greater effect than said first named means, and manu-' for governing-said addi- 14. In combination with an aircraft, a gyroscopic controlling device, a rudder cons trolled therefrom adapted to steer the craft in l a predetermined direction in azimuth, means operable at will, a rudder-actuated thereby having a greater controlling'efiect on the airplane than .said first named rudder, and

meansfor looking said gyroscogewhen said e secondrudder is turned whel" y the idirection'in which the gyroscopic device steers the craft may be altered; v

15. In combination with an aircraft, a gyroscopic controlling device, a rudder con trolled therefrom, in azimuth, other controlling means operable at will, a rudder 'actuatedthereby having a greater controlling effect on the airplane than said first-named rudder,- 'and means selectively broughtw into'action said first-named means for locking said gyroscope for altering-the course; A

16! In an automatic pilot for dirigible I craft, automaticmeans for maintaining a predetermined'straight course,'means oper- .able at will for temporarily changing the 3 course without disturbing said automatic means, whereby, means, the craft automatically resumes its original course,.and means-also operableat will for. permanently alteringgthe means for matic'means.

w coursefinoperating on said auto- In an automatic automatic means pilot for. dirigible adapted to steer the craft 110 by the operation of upon release of saidsecond r for maintaining a predetermined straight ceurse, means 0per-' able at will for temporarily changing the ,course without disturbing said automatic means, whereby, upon release of said second means, the eraft automatically resumes 1ts matic means inoperative;

manently altering the course, including means for temporarily rendering said aut In testimony whereof I have aflixed my signature.

LAWRENGE SPERRY. 

